The present invention relates to a lock device for a power supplying plug connected to a power receiving connector to charge a battery.
Automobile manufacturers are developing electric vehicles (including hybrid vehicles) that use motors as drive sources to lower exhaust gas emissions. In such an electric vehicle, a battery drives the drive source. When the state of charge of the battery becomes low, the battery must be charged using a power supply provided in a household or a charging station. Thus, an electric vehicle includes a charging system that can easily be used by a user. Japanese Laid-Open Patent Publication No. 9-161898 describes such a system. In this system, an inlet (power receiving connector) is arranged in a vehicle. A power supplying plug connected to, for example, a commercial household power supply can be connected to the inlet. A user parks the vehicle at his or her home and connects the power supplying plug to the inlet. This supplies power to the vehicle and charges the battery. The power supplying plug includes a hook and an operation portion. The inlet includes a catch. Engagement of the hook with the catch keeps the power supplying plug connected to the inlet. Operation of the operation portion moves the hook and disengages the hook from the catch. This permits removal of the power supplying plug from the inlet.
The charging of a battery requires a longer time compared to filling a gasoline vehicle with gasoline. Thus, the user will leave the vehicle with the power supplying plug connected to the inlet for a long period. As a result, for example, someone may remove the power supplying plug from the vehicle that is being supplied with power in an unauthorized manner to connect the power supplying plug to another vehicle and steal electricity. The power supplying plug may also be stolen. Accordingly, a lock device for a power supplying plug has been developed to restrict movement of the hook when the battery is being charged. One example of such a lock device includes a motor-driven lock bar. When the hook of the power supplying plug is engaged with the hook, the lock bar fixes the hook at a lock position and prohibits movement of the hook. When the lock bar is in such a lock state, the power supplying plug cannot be removed from the inlet. To remove the power supplying plug from the inlet, the lock bar is moved to an unlock position to permit movement of the hook of the power supplying plug. The lock device includes an unlock switch and a sensor, which detects connection of the inlet and the power supplying plug. When the sensor detects connection, the lock bar is moved from the unlock position to the lock position. When the unlock switch is operated, the lock bar is moved from the lock position to the unlock position.
Japanese Laid-Open Patent Publication No. 2005-194799 describes an example of a smart system installed in a vehicle that performs wireless communication with an electronic key, which is carried by a user, to permit the locking and unlocking of vehicle doors and the starting of the engine only when wireless communication is established. The vehicle intermittently transmits a wireless signal in the LF band to form a transmission area near the vehicle. When the electronic key enters the communication area and receives the LF band wireless signal, the electronic key transmits a wireless signal in the UHF band to the vehicle. When the vehicle determines that the received UHF band wireless signal is correct, the vehicle permits the unlocking of the doors.
To improve security, lock devices for power supplying plugs using a smart system have been developed. Such a lock device includes an antenna that transmits a wireless signal in the LF band in the proximity of the inlet. When the wireless signal from the antenna triggers and establishes communication between the vehicle and the electronic key, the lock device permits removal of the power supplying plug. This further prevents unauthorized removal of the power supplying plug.
However, the wireless signal forming the communication area may be superimposed on the wireless signal from the antenna of the inlet. Superimposed LF band wireless signals interfere with and cancel each other. When such interference occurs, even when the electronic key enters an area in which the LF band wireless signal can be received, the electronic key may not be able to receive the wireless signal. When the electronic key cannot receive the wireless signal, wireless communication is not established between the electronic key and the vehicle. In such a case, the lock device for the power supplying plug does not permit removal of the power supplying plug.